No, that is not possible. /services/data/query is for getting data, not updating it in any way.
However, it is definitely possible to achieve what you're after. Steps:
1) Get the list of objects you want to delete using https://api.clarizen.com/V2.0/services/data/Query
2) A single object can be deleted using https://api.clarizen.com/V2.0/services/data/objects
3) Multiple delete requests can be combined into one using https://api.clarizen.com/V2.0/services/bulk/Execute
The third step is only necessary to improve performance by reducing the number of trips to the server.
I hope this answers your question.